Age displays as "-1871" in email if contact has year of birth

[Rabattkarte]

Steps to reproduce

What action or series of actions is the cause of the issue?

1. Get a reminder for a birthday including the year, e.g. "8. April 1991"
2. see age as "-1871" in email

Expected behavior

I expect the real age to be displayed in the email.

Current behavior

I see age as "-1871", which obviously is wrong.

Context

Google Contacts Events Notifier (Version 5.0.1)

Birthday of the contact for testing purposes: 8. April 1991.

Extended description

not applicable.

[Rabattkarte]

Debugging line 607 of code.gs reveals, that date.getYear() seems broken:

// line.push(Math.round(date.getYear() - event.getProp('year')));
line.push('date.getYear(): ', date.getYear(), ', event.getProp(\'year\'): ', event.getProp('year'), ', calc: ', Math.round(date.getYear() - event.getProp('year')));

Output:

Years: date.getYear(): 119, event.getProp('year'): 2018, calc: -1899

[GioBonvi]

Hello @Rabattkarte: thank you for bringing this up.
This problem was already flagged by another user, but I could not reproduce it, so I was not able to debug it, however you found the source of the problem and by looking aroud some more I think it is linked to the new V8 engine Google Script runs on.

• The Google Script platform is switching to a Javascript V8 engine

  Historically, Apps Script has been powered by Mozilla's Rhino JavaScript interpreter. While Rhino provided a convenient way for Apps Script to execute developer scripts, it also tied Apps Script to a specific JavaScript version (ES5). Apps Script developers can't use more modern JavaScript syntax and features in scripts using the Rhino runtime.
  To address this concern, Apps Script is now supported by the V8 runtime that powers Chrome and Node.js.

• I haven't looked deeply into this, however it seems users can switch old projects to use the new engine with a click on a notification which appears at the top of the page and new users installing the script for the first time may have it enabled by default.
• In the old engine the date.getYear() method returned the full 4-digit year, while in the new engine date.getYear() returns the years passed since 1900: the full 4-digit year is returned by date.getFullYear() instead. (This was described here)

  // Using the new engine.
  var date = new Date(2020, 1, 1);
  console.log(date.getYear());     // "120"
  console.log(date.getFullYear()); // "2020"

• The origin of the bug is probably a mismatch beteween the (deprecated) getYear() method of a JavaScript Date Object and the (perfectly valid) getYear() method of a Google Script DateField Object which is used here in the code.

I am pushing a fix and releasing an updated version to address this. I have looked into the list of caveats regarding migration to the new engine and the rest of the code should work OK: the tests I have run confirm this.

Thank you again @Rabattkarte for solving this!